"I've never done anything while I've been in elective office for my personal gain," he told CNN's "The Situation Room."

The Texas Republican announced in a videotaped statement early Tuesday that he was dropping out of the race to keep his suburban Houston seat in GOP hands and to spare his constituents "a negative personal campaign" in the fall.

DeLay is facing criminal charges stemming from political contributions to Republican candidates in Texas, and two of his former aides have pleaded guilty in a wide-ranging corruption probe of disgraced GOP lobbyist Jack Abramoff.

But DeLay told CNN that probe had nothing to do with his decision to step down.

"There is nothing that connects me to Abramoff or any of the activities that they had," he said. "I am not a target of this investigation. I haven't even been interviewed by these investigators."

The former House majority leader said he will continue to "engage in the important cultural and political battles of our day from outside the arena of the United States House of Representatives."

Goodbye Texas

The resignation will be effective before mid-June, depending on the congressional calendar, said DeLay, who plans to move to Virginia so he'll be ineligible to run for office in Texas, allowing the Republican Party to pick a new nominee.

Despite a sound performance in the March primary -- he fended off three party challengers -- DeLay was no shoo-in had he stayed in the race; former Rep. Nick Lampson, a Democrat, had promised fierce competition for the seat. Lampson was ousted from an adjacent district in 2004 after DeLay and his allies pushed a controversial reapportionment plan through the Texas Legislature. (Watch how DeLay's decision may affect Congress -- 3:26)

That reapportionment ultimately led to DeLay's indictment last year on money-laundering charges when Austin prosecutor Ronnie Earle accused him of steering corporate money to Republican candidates for the state Legislature in 2002. Texas law prohibits the use of corporate money in elections.

DeLay has repeatedly denied any wrongdoing and has accused Earle of waging a personal vendetta.

Dropping out of the race allows Delay to use his left over campaign contributions to help bankroll his legal defense, said Ken Gross, a Washington lawyer who specializes in campaign finance. DeLay had $1.3 million in his coffers in mid-February, according to federal campaign-finance records.

DeLay was obliged to step aside as House majority leader after the indictment, and Democrats labeled him the poster boy for a "culture of corruption" embraced by GOP leaders on Capitol Hill.

Aides & Abramoff

DeLay took another hit when Abramoff, his longtime friend, pleaded guilty to fraud, corruption and tax evasion in January. Abramoff has been cooperating with authorities investigating influence peddling in Washington.

Also, two former aides to the congressman have admitted involvement in fraud or corruption scandals.

DeLay's former deputy chief of staff Tony Rudy pleaded guilty last week to conspiracy to commit mail and wire fraud, which included violating lobbying restrictions placed on former congressional staffers. Another aide, Michael Scanlon, was Abramoff's business partner and pleaded guilty in November to bilking Indian tribes out of millions of dollars and providing gifts to members of Congress in return for official favors. (Watch DeLay distance himself from his former aides, associates -- 10:06)

DeLay, who denies any impropriety in the Abramoff case, said Tuesday he remains unfazed by the guilty pleas of his former associates.

"I will be quite content to be judged when the passage of time has provided both all the facts and a greater sense of perspective than is possible for most today," he said.

DeLay's attorney Richard Cullen said his client was "bitterly disappointed" by his former aides' admissions, but "as long as people are telling the truth, Mr. DeLay has no fear about this investigation."

Partisan reaction

Reaction to DeLay's resignation was split along party lines. While House Majority Leader John Boehner, R-Ohio, called him "one of the most effective whips we've seen in the Congress" and Republican Rep. Roy Blunt of Missouri said DeLay is "a politician who's been driven by ideals."

Democrats hummed a different tune.

Saying DeLay's resignation is "good for the country," Democratic Chairman Howard Dean said, "The big problem with the Republicans is they put their party in front of their country. Tom DeLay did it. Others have done it."

"This isn't just about Tom Delay, although he's just the ringleader," Pelosi said. "It's about the Republicans in Congress who enabled and benefited from this corruption."

But Blunt insisted that DeLay, by abandoning his bid for re-election, was acting only in the best interest of his constituents -- and not out of fear that his alleged improprieties could damage the Republican Party.

"I think he saw this campaign becoming more about him than the ideas that our party stands for, and decided he wanted to focus the election and his home district in Texas just like we want to focus this election in the country about the ideas our party stands for," Blunt said.

First elected to Congress in 1984, DeLay became House majority whip when Republicans took control of Congress after the 1994 midterm election. DeLay earned his nickname, "The Hammer," for his ability -- his opponents would say his style -- of securing votes on the House floor. (Profile)

After fellow Texan Dick Armey retired as majority leader in 2002, DeLay stepped into the position, the No. 2 post in the House.

While popular with his GOP colleagues, DeLay -- admonished three times by the bipartisan House Ethics Committee in 2004 -- was a lightning rod for criticism from Democrats.